title: Red-green colour blindness in Singaporean children.
abstract: OBJECTIVE
  X-linked red-green colour blindness is the most common form of colour blindness. Various studies suggest that, worldwide, 2-8% of men are afflicted with this condition. The purpose of this study is to determine the prevalence of red-green colour blindness in Singaporean schoolchildren.
  
  
  METHODS
  A total of 1249 children aged 13-15 years were screened using the Ishihara 24-plate edition book during the School Cohort study of the Risk factors for Myopia visit.
  
  
  RESULTS
  A total of 1210 children (96.8%) managed to correctly identify at least 13 of the initial 15 plates and were deemed to have normal colour vision.Thirty-three children (32 boys, one girl) were only able to identify nine or less plates and were considered to be colour blind. Overall, 5.4% (95% confidence interval 3%, 7%) of Chinese, 4.9% (1%, 9%) of Malay and 4.9% (2%, 11%) of Indian boys were colour blind (P = 0.97). Classification plates 16-17 were useful in determining deutran or protan tendencies in only 14 (43%) of the 33 children identified as being colour blind.
  
  
  CONCLUSIONS
  5.3% of boys and 0.2% of girls were found to be colour blind in this Singapore-based study. Although the Ishihara test proved useful in identifying colour-blind children, other tests are required to accurately classify the types of red-green colour blindness in these children.
authors.affiliation: Singapore Eye Research Institute, Singapore. wla_chia@yahoo.com
authors.forename: Audrey
authors.initials: A
authors.lastname: Chia
authors.forename: Gus
authors.initials: G
authors.lastname: Gazzard
authors.forename: Louis
authors.initials: L
authors.lastname: Tong
authors.forename: Xiaoe
authors.initials: X
authors.lastname: Zhang
authors.forename: Ee-Ling
authors.initials: EL
authors.lastname: Sim
authors.forename: Allan
authors.initials: A
authors.lastname: Fong
authors.forename: Seang
authors.initials: S
authors.lastname: Mei Saw
mesh_terms: D000293:Adolescent; D044466:Asian People / Q000706:statistics & numerical data; D041321:Chromosomes, Human, X; D015331:Cohort Studies; D003117:Color Vision Defects / Q000175:diagnosis / Q000453:epidemiology* / Q000208:ethnology / Q000235:genetics; D003941:Diagnostic Techniques, Ophthalmological; D005260:Female; D008040:Genetic Linkage; D006801:Humans; D007194:India / Q000208:ethnology; D008297:Male; D015995:Prevalence; D017678:Sex Distribution; D012846:Singapore / Q000453:epidemiology